Lighting Design Glossary

Photopic Vision

(Term of physiology)

Photopic vision is the scientific term for human color vision under
normal lighting conditions during the day.

In the range above 3.4 cd/m², the human eye uses three
types of cones to sense light in three respective bands of color.
The pigments of the cones have maximum absorption values at
wavelengths of about
445 nm (blue), 535 nm (green), resp. 575 nm (red).
Their sensitivity ranges overlap to provide continuous (but not linear)
vision throughout the visual spectrum. The maximum efficacy is
683 lumens/W at a wavelength of 555 nm (yellow).